Air compressor for blowing out lines

[jgourlie]

Originally Posted by RamblerGuy

What's the problem with 40 psig? The system is rated for at least 150 psig and is protected at 150 psig by the water heater pressure relief valve. You won't hurt the system with any pressure up to 150 psig, you'll just blow water all over if you leave a faucet open or when you open it. If you're comfortable with 40 psig, use it. If you like 30 psig and it clears your lines, use it.

Consider the argument that you need a pressure regulator on the incoming city water line or you'll have leaks. Why? You can get high pressure on the system anyway. If you use hot water and the water heater then heats water with no faucets open, the expansion of the water will cause the pressure to rise. If there's not enough air in the water heater to absorb this expansion, the pressure can cause the relief valve to weep until the pressure drops. I have that happen often and it's never caused a problem with the plumbing. It can make it hard to open the toilet water valve, but I just reach over and open the hot water on the sink for a second.

Great points!

[KingFisher]

I use a little 100v compressor I bought in Florida last winter at True Value for $99.

A piece of cut off garden hose with a qd fitting in the cut end.

I'm glad I came across this thread because it reminded me that when I blew out the lines on my sunset trail yesterday I forgot to do the outside shower, so now I have to go do it again.

[thundrr1]

Originally Posted by RedLdr1

My old Sears shop vacuum blows out a ton of dust, and other "stuff", when I set it up for blower mode. I would not want that "stuff" getting in my water lines! A newer, cleaner vac might not be as bad as my oldie but I would be very hesitant to try it...

Thanks, a great point. Thanks. I'll adapt the pancake compressor.


George

[MNtraveler]

Originally Posted by RamblerGuy

What's the problem with 40 psig? The system is rated for at least 150 psig and is protected at 150 psig by the water heater pressure relief valve. You won't hurt the system with any pressure up to 150 psig, you'll just blow water all over if you leave a faucet open or when you open it. If you're comfortable with 40 psig, use it. If you like 30 psig and it clears your lines, use it.

Consider the argument that you need a pressure regulator on the incoming city water line or you'll have leaks. Why? You can get high pressure on the system anyway. If you use hot water and the water heater then heats water with no faucets open, the expansion of the water will cause the pressure to rise. If there's not enough air in the water heater to absorb this expansion, the pressure can cause the relief valve to weep until the pressure drops. I have that happen often and it's never caused a problem with the plumbing. It can make it hard to open the toilet water valve, but I just reach over and open the hot water on the sink for a second.

I don't think that rating is correct but I'll let the experts comment. I just wanted to point out the water heater should be bypassed when blowing out the lines. The WH is drained and there is no point trying to blow out what's left in the bottom or the 6-12 gallon tank. So no pressure relief valve is online at the time.


Land of 10,000 Lakes
2016 Forester MBS 2401R
Nights camped 2016: 29; RV to date: 32

[MNtraveler]

Thanks for all the comments here. Just to follow up, I concluded that our small home compressor that we use for bicycle tires was not up to the job. I bought a blowout plug adapter from Camping World. I was going to connect it to a line at a service station, but realized that the pressure would be too high and I would have no way to control it. However, rather than buying an air pressure regulator, I realized that my home compressor has a pressure regulator built into it. I was able to remove that from the compressor and attach it to the blowout plug. The other thing I needed to buy was the air chuck connector that screws into the line, in this case into the pressure regulator. With this system assembled, I found our local service station was willing to lend me their air line for a few minutes at no charge. However, the air chuck they use is a different size from what I had purchased. I was fortunately able to borrow the right connector from one of the mechanics and screw it into the line. With that in place, I was able to connect the airline and start with no pressure, then use the pressure regulator to dial the pressure up to 40-50 psi and everything went well. One thing I would do differently next time is instead of buying the single air chuck connector, for an additional $5 purchase a packet with four or five different types, because apparently different places use different sizes of these.


Land of 10,000 Lakes
2016 Forester MBS 2401R
Nights camped 2016: 29; RV to date: 32

[Davidceder]

I have my water pressure regulator attached at the city water input. I leave it there permanently. If I blow the lines through the water pressure regulator will it regulate the air pressure as well? Do I need to use MORE pressure as I am going through the regulator?

Just a thought

[5picker]

Originally Posted by Davidceder

I have my water pressure regulator attached at the city water input. I leave it there permanently. If I blow the lines through the water pressure regulator will it regulate the air pressure as well? Do I need to use MORE pressure as I am going through the regulator?

Just a thought

In theory yes... but I would not trust a water pressure regulator for air regulating use.

The diaphragm in a water pressure regulator is designed for 'wetted' contact by the fluid. (water) It may not behave the same with air.

[MNtraveler]

Agreed.


Land of 10,000 Lakes
2016 Forester MBS 2401R
Nights camped 2016: 32; RV to date: 35

[325BH]

Originally Posted by 5picker

In theory yes... but I would not trust a water pressure regulator for air regulating use.



The diaphragm in a water pressure regulator is designed for 'wetted' contact by the fluid. (water) It may not behave the same with air.

In addition, the water "regulator" that we use for our camper's water inlet isn't a real regulator. It simply blocks flow once a pressure threshold is met. A real regulator (that we are talking about with the air compressor) actually releases pressure to stabilize. The difference may seem irrelevant, however it is important when using high pressure. Using the water "regulator" could allow too much pressure to build during the initial jolt when connecting the air hose.

This may be a problem and it may not be. Just trying to help.

Most (all) air compressors have regulators, since the tank pressure is usually higher than the desired hose pressure.

Although I use the water "regulator" for camping, I have always wondered how well it works-- if at all.

[Davidceder]

In the future I will remove the water regulator prior to blowing the lines and use the pressure regulator on the compressor. Not a big issue!

[jonnys_walkers]

I don't blow the tanks. I pull the hot water anode and hook up the wet/dry vacuum up and suck all the water back through the hot water tank.